In the related art, wireless communication systems, where multiple wireless nodes are connected to each other in a mesh-like manner, are in use. As a communication scheme for such wireless communication systems, for example, a time division communication system is employed. In the time division communication system, timings for the respective wireless nodes to go to sleep can be easily controlled, and thus, the power of the wireless communication systems can be saved.
However, in the time division communication system of the related art, uplink and downlink transmission are performed at the same frequency. Due to this, when a transmission frequency required for uplink and that required for downlink are different, excessive data transmission is performed, thereby disadvantageously increasing power consumption.